In the jewelers art it is common practice for a jeweler to enlarge or reduce the diameter of a finger ring to fit the finger of a user of the ring. This is normally accomplished by clamping the ring in a vise or other clamping device and then making a radial cut manually through the annulus of the ring by a hacksaw or other sawing device to remove a radial segment of the annulus.
If the diameter of the ring is to be enlarged, after a thin saw cut is made through its annulus its diameter is enlarged on a mandrel and an independent annulus segment of correct length is soldered into the opening formed in the annulus, resulting in a desired enlargement of the diameter and circumference of the ring.
If the diameter of the ring is to be reduced, its circumference must be reduced, frequently from 0.100 to 0.300 inches. This requires several separate saw cuts through the annulus to remove a segment of sufficient size, as saw blades normally employed for such purpose are less than 0.100 inches thick. The ring is then put on a mandrel and its circumference reduced to bring the edges of the total cut together following which they are soldered together, resulting in a ring of the desired reduced diameter and circumference. It is difficult, if not impossible, to make such cuts truly radial when the saw is held manually, resulting in the edges of the total cut not being parallel when the ring circumference is so reduced to bring such edges into engagement, which in turn makes soldering difficult and frequently results in a faulty appearance of the ring, which is undesirable.
In using a thin straight hacksaw blade or a thin power driven circular saw blade to make such conventional cuts through a ring the blades frequently break, due to manual relative twisting of the ring and saw blade during sawing, which requires replacement of the blade at substantial expense for blades and loss of labor time in the operation, both of which are undesirable.
Also, in employing such conventional manual method of making several cuts in a ring it is difficult, if not impossible, to optically gauge the proper desired separation of such cuts to result in a ring of the precise desired circumference, which is another disadvantage of such conventional method and practice.